What was the meaning of the riddle?

In the game, Geron is asked by Fahi to explain the meaning of an inscription:

As the stone rules over the scarab, so rules the scarab over the stone. Enter if to you the answer is known. If not, then forever your life I'll own.

As we find out in the end,

the riddle is irrelevant to the story, as Sadja couldn't read it. So the heroes stop trying to decipher it.

Earilier, Geron offered an explanation for the riddle,

saying that it referred to how the mechanism for opening the stone door had the shape of a scarab, so the riddle must have been a hint for opening the door.

Fahi however pointed out that

the inscription appeared only after the door was opened, so it couldn't have been a clue for how to open it.

Despite the revelation at the end, Fahi's point stands.

Is there an explanation, whether in the game itself or in other material (from what I understand, The Dark Eye is a franchise with a lot of stories) for what the inscription meant?

The inscription only appear after the door is opened because it is a Warning, not for those wanting to enter but for those wanting to get out alive, the so called "riddle" does not tell you how to enter, but warns those entering on maintaining the ability to get out, as it basically warns you that if the scarab key is damaged then the chamber will own your life forever, this much the mage already knew at the start, the real riddle though is not the answer to the "warn-riddle" inscription, but what was Sadja's answer to the riddle, it is her answer we are looking for, wich at the end we discover: she had none.